There can be little debate the Steelers have the best linebackers in the league. The proof is overwhelming.

James Harrison, who set a Steelers record with 16 sacks, earned NFL defensive player of the year. James Farrior made his second Pro Bowl. LaMarr Woodley, who should have made the Pro Bowl, had 11 1/2 sacks and then six more in three postseason games. Lawrence Timmons moves into the starting lineup after a successful run as their nickel linebacker in 2008 when he had five sacks.

Oh, and they helped their defense become the best in the NFL and to win a Super Bowl.

What's next for this group? That's the point, what is next, what lies behind this dominating starting four? If one or two are unable to play, what then?

That is what their coaches are trying to determine as training camp winds down and the second exhibition game draws near. Last season, Timmons was that man. He not only was the top backup at inside linebacker, he was the first man in on the outside as well, where he started two games in 2008. Larry Foote's departure changed that.

A season earlier, James Harrison was the top backup at the two outside positions.

Can one become the next James Harrison? The Steelers would settle for someone merely becoming a good replacement should Harrison or any of their starting linebackers be injured.

"James Harrison had the same thing happen to him," said Farrior, captain of the defense. "He had to wait, and when he got his opportunity, he proved he could play. I feel, given the opportunity, those guys can play and do well."

Farrior and the rest of the starters, of course, hope that opportunity does not happen because it would mean an injury or more. It's rare for all four starting linebackers to start every game, but it almost happened last season. Woodley and Harrison each missed one game of the 19 through the Super Bowl. Foote and Farrior started all of them.

If something happens to any of them this season, the first man up on the inside would be Fox, followed by Woods. The first to step up on the outside would be Frazier with the next several weeks to determine who might be next. Davis, a third-round draft pick in 2008, has the disadvantage of not being a very good special teams player, but he performed well at his position against Arizona Thursday.

Fox signed a one-year contract in 2008 as an unrestricted free agent from Kansas City, was great on special teams, and returned under a two-year deal this season. He does not care if not many people know who he or other backup linebackers are at the moment.

"We have guys who are capable and willing to step in," he said.

Frazier has followed in the footsteps of Harrison, although it's normally not the recommended path. Signed as an undrafted rookie from Cincinnati in 2005, he was cut by the Steelers, then put on the practice squad, then signed again. His right leg was broken in the AFC title game, and he was released on the final 2006 cut. He and coach Bill Cowher had a tiff along the sideline that summer.

"We talked; he said that wasn't the reason," Frazier said yesterday.

He spent the '06 season with his hometown Cincinnati Bengals, who cut him after one game in '07, when the Steelers quickly signed him. He has been with them since as a backup and special teams player. At 28 and having been cut three times by two teams, Frazier is approaching the age when Harrison became an overnight sensation after he was cut three times by two teams.

"Nobody really knew about him," Frazier said, "but just like us he was a hard worker, he did what he had to do, he focused on special teams and when he got his chance he excelled."

At least one disparity exists between Harrison and Frazier. Both weigh in the mid-240s but Harrison stands 6 feet and Frazier is 6-5. The advantages Harrison has on leverage, Frazier has elsewhere.

"I have longer arms, I can keep people off of me," said Frazier, who like many a Steelers outside linebacker played end in college. "I feel I have good stride. I have a lot of things I bring to the table."

The table is set for the front four linebackers; it's the second course that remains unknown.